Tracking sub-clonal TP53 mutated tumor cells in human metastatic renal cell carcinoma.

Guilhem Bousquet,Diane Damotte,Mariana Varna,Irmine Ferreira,Maxime Battistella,Jean-Paul Feugeas,Christophe Leboeuf,Louis-François Plassa,Diaddin Hamdan,Philippe Bertheau,Morad El Bouchtaoui,Anne Janin

doi:10.18632/oncotarget.4220

Abstract

Renal Cell Carcinomas (RCCs) are heterogeneous tumors with late acquisition of TP53 abnormalities during their evolution. They harbor TP53 abnormalities in their metastases. We aimed to study TP53 gene alterations in tissue samples from primary and metastatic RCCs in 36 patients followed up over a median of 4.2 years, and in xenografted issued from primary RCCs. In 36 primary RCCs systematically xenografted in mice, and in biopsies of metastases performed whenever possible during patient follow-up, we studied p53-expressing tumor cells and TP53 gene abnormalities.We identified TP53 gene alterations in primary tumors, metastases and xenografts. Quantification of tumors cells with TP53 gene alterations showed a significant increase in the metastases compared to the primary RCCs, and, strikingly, the xenografts were similar to the metastases and not to the primary RCCs from which they were derived.Using laser-microdissection of p53-expressing tumor cells, we identified TP53-mutated tumor cells in the xenografts derived from the primary RCC, and in a lung metastasis later developed in one patient. The mutation enabled us to track back their origin to a minority sub-clone in the primary heterogeneous RCC. Combining in situ and molecular analyses, we demonstrated a clonal expansion in a living patient with metastatic RCC.

Highlights

Metastatic renal cell carcinoma (RCC) is a severe disease with median survival of between 7 and 30 months [1, 2]
In 36 primary RCCs systematically xenografted in mice, and in biopsies of metastases performed whenever possible during patient follow-up, we studied p53expressing tumor cells and TP53 gene abnormalities
Using Fluorescent in situ hybridization (FISH) for TP53 on the same samples (Figure 1C and Supplementary Table 2), we found a significant increase in abnormalities of TP53 gene copy numbers when primary RCCs were compared to their corresponding metastases (17.8% vs. 34.7%, p < 0.01)

Summary

Introduction

Metastatic renal cell carcinoma (RCC) is a severe disease with median survival of between 7 and 30 months [1, 2]. Twenty-five percent of patients with localized RCC develop metastases, but clinical and biological factors predicting metastatic risk are not reliable enough to guide RCC therapies at a localized stage. This could be linked to heterogeneity of the tumor cells, recently characterized in primary RCCs [3, 4, 5]. On metastatic samples from the autopsy of a patient with prostate cancer, the lethal metastatic clone had genomic alterations, including a TP53 mutation, which enabled to track its origin back to a minority sub-clone with the same TP53 mutation in the primary tumor [11]

Objectives

Methods

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Conclusion